1 /* $NetBSD: mdreloc.c,v 1.30 2014/08/25 20:40:52 joerg Exp $ */
2
3 #include <sys/cdefs.h>
4 #ifndef lint
5 __RCSID("$NetBSD: mdreloc.c,v 1.30 2014/08/25 20:40:52 joerg Exp $");
6 #endif /* not lint */
7
8 #include <sys/cdefs.h>
9 #ifndef lint
10 __RCSID("$NetBSD: mdreloc.c,v 1.30 2014/08/25 20:40:52 joerg Exp $");
11 #endif /* not lint */
12
13 #include <sys/types.h>
14
15 #include "debug.h"
16 #include "rtld.h"
17
18 void _rtld_bind_start(void);
19 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
20 caddr_t _rtld_bind(const Obj_Entry *, Elf_Word);
21 static inline int _rtld_relocate_plt_object(const Obj_Entry *,
22 const Elf_Rela *, Elf_Addr *);
23
24
25 void
_rtld_setup_pltgot(const Obj_Entry * obj)26 _rtld_setup_pltgot(const Obj_Entry *obj)
27 {
28 obj->pltgot[1] = (Elf_Addr) obj;
29 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
30 }
31
32 void
_rtld_relocate_nonplt_self(Elf_Dyn * dynp,Elf_Addr relocbase)33 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
34 {
35 const Elf_Rela *rela = 0, *relalim;
36 Elf_Addr relasz = 0;
37 Elf_Addr *where;
38
39 for (; dynp->d_tag != DT_NULL; dynp++) {
40 switch (dynp->d_tag) {
41 case DT_RELA:
42 rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr);
43 break;
44 case DT_RELASZ:
45 relasz = dynp->d_un.d_val;
46 break;
47 }
48 }
49 relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz);
50 for (; rela < relalim; rela++) {
51 where = (Elf_Addr *)(relocbase + rela->r_offset);
52 *where += (Elf_Addr)relocbase;
53 }
54 }
55
56 int
_rtld_relocate_nonplt_objects(Obj_Entry * obj)57 _rtld_relocate_nonplt_objects(Obj_Entry *obj)
58 {
59 const Elf_Rela *rela;
60
61 for (rela = obj->rela; rela < obj->relalim; rela++) {
62 Elf_Addr *where;
63 const Elf_Sym *def;
64 const Obj_Entry *defobj;
65 Elf_Addr tmp;
66 unsigned long symnum;
67
68 where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
69 symnum = ELF_R_SYM(rela->r_info);
70
71 switch (ELF_R_TYPE(rela->r_info)) {
72 case R_TYPE(NONE):
73 break;
74
75 #if 1 /* XXX should not occur */
76 case R_TYPE(PC32):
77 def = _rtld_find_symdef(symnum, obj, &defobj, false);
78 if (def == NULL)
79 return -1;
80
81 tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
82 rela->r_addend) - (Elf_Addr)where;
83 if (*where != tmp)
84 *where = tmp;
85 rdbg(("PC32 %s in %s --> %p in %s",
86 obj->strtab + obj->symtab[symnum].st_name,
87 obj->path, (void *)*where, defobj->path));
88 break;
89
90 case R_TYPE(GOT32):
91 #endif
92 case R_TYPE(32):
93 case R_TYPE(GLOB_DAT):
94 def = _rtld_find_symdef(symnum, obj, &defobj, false);
95 if (def == NULL)
96 return -1;
97
98 tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
99 rela->r_addend);
100 if (*where != tmp)
101 *where = tmp;
102 rdbg(("32/GLOB_DAT %s in %s --> %p in %s",
103 obj->strtab + obj->symtab[symnum].st_name,
104 obj->path, (void *)*where, defobj->path));
105 break;
106
107 case R_TYPE(RELATIVE):
108 *where += (Elf_Addr)obj->relocbase;
109 rdbg(("RELATIVE in %s --> %p", obj->path,
110 (void *)*where));
111 break;
112
113 case R_TYPE(COPY):
114 /*
115 * These are deferred until all other relocations have
116 * been done. All we do here is make sure that the
117 * COPY relocation is not in a shared library. They
118 * are allowed only in executable files.
119 */
120 if (obj->isdynamic) {
121 _rtld_error(
122 "%s: Unexpected R_COPY relocation in shared library",
123 obj->path);
124 return -1;
125 }
126 rdbg(("COPY (avoid in main)"));
127 break;
128
129 case R_TYPE(TLS_DTPMOD32):
130 def = _rtld_find_symdef(symnum, obj, &defobj, false);
131 if (def == NULL)
132 return -1;
133
134 *where = (Elf_Addr)defobj->tlsindex;
135 rdbg(("DTPMOD32 %s in %s --> %p in %s",
136 obj->strtab + obj->symtab[symnum].st_name,
137 obj->path, (void *)*where, defobj->path));
138 break;
139
140 case R_TYPE(TLS_DTPREL32):
141 def = _rtld_find_symdef(symnum, obj, &defobj, false);
142 if (def == NULL)
143 return -1;
144
145 if (!defobj->tls_done && _rtld_tls_offset_allocate(obj))
146 return -1;
147
148 *where = (Elf_Addr)(def->st_value + rela->r_addend
149 - TLS_DTV_OFFSET);
150 rdbg(("DTPREL32 %s in %s --> %p in %s",
151 obj->strtab + obj->symtab[symnum].st_name,
152 obj->path, (void *)*where, defobj->path));
153 break;
154
155 case R_TYPE(TLS_TPREL32):
156 def = _rtld_find_symdef(symnum, obj, &defobj, false);
157 if (def == NULL)
158 return -1;
159
160 if (!defobj->tls_done && _rtld_tls_offset_allocate(obj))
161 return -1;
162
163 *where = (Elf_Addr)(def->st_value + rela->r_addend
164 + defobj->tlsoffset - TLS_TP_OFFSET);
165 rdbg(("TPREL32 %s in %s --> %p in %s",
166 obj->strtab + obj->symtab[symnum].st_name,
167 obj->path, (void *)*where, defobj->path));
168 break;
169
170 default:
171 rdbg(("sym = %lu, type = %lu, offset = %p, "
172 "addend = %p, contents = %p, symbol = %s",
173 symnum, (u_long)ELF_R_TYPE(rela->r_info),
174 (void *)rela->r_offset, (void *)rela->r_addend,
175 (void *)*where,
176 obj->strtab + obj->symtab[symnum].st_name));
177 _rtld_error("%s: Unsupported relocation type %ld "
178 "in non-PLT relocations",
179 obj->path, (u_long) ELF_R_TYPE(rela->r_info));
180 return -1;
181 }
182 }
183 return 0;
184 }
185
186 int
_rtld_relocate_plt_lazy(const Obj_Entry * obj)187 _rtld_relocate_plt_lazy(const Obj_Entry *obj)
188 {
189 const Elf_Rela *rela;
190
191 if (!obj->relocbase)
192 return 0;
193
194 for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) {
195 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
196
197 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT));
198
199 /* Just relocate the GOT slots pointing into the PLT */
200 *where += (Elf_Addr)obj->relocbase;
201 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where));
202 }
203
204 return 0;
205 }
206
207 static inline int
_rtld_relocate_plt_object(const Obj_Entry * obj,const Elf_Rela * rela,Elf_Addr * tp)208 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela,
209 Elf_Addr *tp)
210 {
211 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
212 Elf_Addr new_value;
213 const Elf_Sym *def;
214 const Obj_Entry *defobj;
215 unsigned long info = rela->r_info;
216
217 assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT));
218
219 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL);
220 if (__predict_false(def == NULL))
221 return -1;
222 if (__predict_false(def == &_rtld_sym_zero))
223 return 0;
224
225 assert(rela->r_addend == 0);
226 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
227 if (tp == NULL)
228 return 0;
229 new_value = _rtld_resolve_ifunc(defobj, def);
230 } else {
231 new_value = (Elf_Addr)(defobj->relocbase + def->st_value +
232 rela->r_addend);
233 }
234 rdbg(("bind now/fixup in %s --> old=%p new=%p",
235 defobj->strtab + def->st_name, (void *)*where, (void *)new_value));
236 if (*where != new_value)
237 *where = new_value;
238
239 if (tp)
240 *tp = new_value - rela->r_addend;
241
242 return 0;
243 }
244
245 caddr_t
_rtld_bind(const Obj_Entry * obj,Elf_Word reloff)246 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
247 {
248 const Elf_Rela *rela = (const Elf_Rela *)((const uint8_t *)obj->pltrela + reloff);
249 Elf_Addr result;
250 int err;
251
252 result = 0; /* XXX gcc */
253
254 _rtld_shared_enter();
255 err = _rtld_relocate_plt_object(obj, rela, &result);
256 if (err)
257 _rtld_die();
258 _rtld_shared_exit();
259
260 return (caddr_t)result;
261 }
262
263 int
_rtld_relocate_plt_objects(const Obj_Entry * obj)264 _rtld_relocate_plt_objects(const Obj_Entry *obj)
265 {
266 const Elf_Rela *rela;
267
268 for (rela = obj->pltrela; rela < obj->pltrelalim; rela++)
269 if (_rtld_relocate_plt_object(obj, rela, NULL) < 0)
270 return -1;
271
272 return 0;
273 }
274